Police have informed some of Trinity Mirror's Sunday journalists that they may have been victims of phone hacking with their names appearing on the notebooks of Glenn Mulcaire (pictured), employed by rival News of the World.
Photograph: Rex Features

A handful of journalists working for Trinity Mirror's Sunday titles have been told that they may have been victims of phone hacking by News of the World, in an apparent sign that the Murdoch title sought to eavesdrop on to news being gathered by its principal competitors.

Lee Harpin, head of news at the People, is among three newsdesk executives at both that newspaper and the Sunday Mirror, who have been told by the Metropolitan police that their details appear in the notebooks kept by Glenn Mulcaire, the private investigator who undertook hacking for News of the World.

Trinity Mirror – the owner of the People and Sunday Mirror – has long suspected that its employees were targeted given the intense rivalry that exists in the Sunday redtop market. But it is the first time the company has learned that any of its journalists or other executives may have been victims.

News of the World was the market leading title, with sales of 2.67m at the time of its closure last July. The Sunday Mirror briefly became the redtop market leader, but with the launch of the Sun's Sunday edition, has settled back down to second place with about 1.1m in sales, according to early industry estimates. The smaller People is currently selling an estimated 465,000.

Trinity Mirror declined to comment.

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